Thumbhole stock



FIG. 1 is a left side elevational view of a thumbhole stock, showing our new design;

FIG. 2 is a right side elevational view thereof;

FIG. 3 is a top view thereof;

FIG. 4 is a bottom view thereof;

FIG. 5 is a rear elevational view thereof; and,

FIG. 6 is a front elevational view thereof.

The broken lines showing the additional structures in 1 through 6 are for illustrative purposes only, and form no part of the claimed design. 

The ornamental design for a thumbhole stock, as shown and described. 